Address Decoding

The 21555 provides a semaphore method that may be used to guarantee atomicity of the address and data register accesses using the Upstream Configuration Own bit and Downstream Configuration Own bit. Atomicity of these accesses is not guaranteed in hardware. When the corresponding Configuration Enable bit is not set, the Own bit is treated as reserved. The following procedure should be used for downstream transactions:

1.The initiator of the transaction should read the Downstream Configuration Own bit for initiation of transactions on the secondary bus. When the bit reads as zero, the initiator may proceed with the configuration transaction sequence. When the bit reads as a one, the initiator should not proceed until a subsequent read of the own bit returns a 0 (zero). The 21555 automatically sets the own bit to a 1 after it is read.

2.The initiator should write the target configuration address in the Downstream Configuration Address register.

3.The initiator should write or read the data in the Downstream Configuration Data register until a response other than target retry is received.

4.Upon completion of the configuration transaction on the initiator bus, the 21555 automatically clears the Downstream Configuration Own bit to a 0.

Upstream configuration transactions should use a similar process. To check the status of the own bits without read side effects, read only copies of these bits are located in the Configuration CSR. Byte access of the Configuration Own bits and their read-only copies should be used to avoid setting the Configuration Own bit for the opposite interface.

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21555 Non-Transparent PCI-to-PCI Bridge User Manual

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Intel 21555 user manual Address Decoding
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21555 specifications

The Intel 21555 is a prominent microprocessor developed by Intel, designed to cater to a variety of computing needs. This processor marks a significant step forward in Intel's lineup and underscores the company's commitment to advancing technology in personal computing, enterprise solutions, and beyond.

One of the standout features of the Intel 21555 is its advanced architecture. It utilizes a multi-core design, enabling improved performance through parallel processing. This architecture allows multiple applications to run seamlessly without a decline in speed. The cores are built on a cutting-edge manufacturing process that enhances energy efficiency while maintaining high clock speeds.

The Intel 21555 supports a wide range of technologies, including Intel Turbo Boost, which enables dynamic adjustments to the processor’s performance based on workload demands. This feature allows the processor to accelerate its speed during intensive tasks, providing users with a responsive experience when it matters the most.

Another key characteristic of the Intel 21555 is its support for integrated graphics. With Intel UHD Graphics technology, users can enjoy enhanced visuals for everyday tasks such as video playback, web browsing, and light gaming. This eliminates the need for a separate graphics card for many users, particularly in home office or light gaming scenarios.

Security is a significant focus in the design of the Intel 21555. It includes built-in hardware-based security features like Intel Trusted Execution Technology and Secure Boot. These features help protect against various types of threats, ensuring that user data remains secure from malicious attacks.

The Intel 21555 is also optimized for use with Intel's platform technologies, including Intel Optane memory and Intel Rapid Storage Technology. These technologies work together to deliver faster boot times and improved system responsiveness, making computing more efficient for users.

Furthermore, the Intel 21555 is designed to support virtualization technologies, allowing multiple operating systems to run concurrently without compromising performance. This is particularly useful for developers and businesses that rely on virtualization for testing and development environments.

In summary, the Intel 21555 is a powerful and versatile processor that reflects Intel's ongoing innovation in the computing space. With its multi-core architecture, enhanced graphics capabilities, strong security features, and advanced technologies, it stands out as an excellent choice for a wide range of applications, serving both casual users and professionals alike.
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